1. Field of the Invention
The present invention generally relates to a sliding module, and more particularly, to a sliding module for a sliding-type portable communication device in which two housings are coupled to each other in a manner that one housing longitudinally moves to be opened or closed with respect to the other while the housings face each other.
2. Description of the Related Art
Generally, a “portable communication device” refers to an apparatus which a user can carry with him/her to perform wireless communication with another party, either by voice or, for example, text messages. Conventional portable communication devices may be classified into various types according to their appearance, such as bar-type terminals, flip-type terminals, folder-type terminals, etc.
A bar-type terminal has a single housing shaped like a candy bar. A flip-type terminal has a flip which is rotatably combined with a bar-shaped housing by a hinge device. A folder-type terminal has a folder pivotably coupled to a single bar-shaped housing by a hinge device.
In addition, portable communication devices may be classified into rotation-type terminals and sliding-type terminals according to different ways of opening and closing the terminals.
For example, in a rotation-type terminal, two housings are coupled to each other in such a manner that one housing rotates to be opened or closed with respect to the other while the housings face each other.
Moreover, in a sliding-type terminal, two housings are coupled to each other in such a manner that one housing longitudinally moves to be opened or closed with respect to the other while the housings face each other. These variously-classified portable communication devices can be easily understood by those skilled in the art.
As shown in the exploded view of FIG. 1, a sliding module 1 for a sliding-type portable communication device may be structured such that when viewed from a main body 2 includes a keypad with a plurality of keys 2a and a microphone 2b, a sliding portion 3 that slidably extends from the footprint of the main body by about ½ of the length of the main body 2 to open the device for access of the keys 2a or retracts back to the footprint of the main body when closed. Generally, a 3×4 keypad may be installed in the main body 2, and a speaker device 3a and a Liquid Crystal Display (LCD) module 3b may be installed on a front surface of the sliding portion 3.
As shown in FIGS. 1 and 2, the conventional sliding module 1 for the sliding-type portable communication device includes the main body 2, the sliding portion 3 sliding a predetermined length on the main body 2, and a plurality of torsion springs 4 arranged between the sliding portion 3 and the main body 2 to provide an elastic force for allowing the sliding portion 3 to slide up or down. Between the main body 2 and the sliding portion 3 is also provided a guide portion 6 for guiding the sliding portion 3 along the main body 2 when in motion.
The guide portion 6 includes a main plate 6a having a pair of guide rails 6c, and a sliding plate 6b having a guide member 6d. 
As shown in FIG. 2, the thickness of the sliding-type portable communication device is determined according to mounting positions of the LCD module 3b and the sliding module 1. In particular, a smart phone and a portable communication device sliding horizontally have to include the large-size LCD module 3b in the sliding portion 3, such that the sliding module 1 is provided under the LCD module 3b. 
However, the conventional sliding module for the sliding-type portable communication device is positioned outside the large-size LCD module, and the sliding module has the sliding plate in the sliding portion thereof. As a result, in the conventional sliding module the size and thickness of the sliding plate cannot be reduced from its present thickness, thereby increasing the overall size of the communication device and thus hindering the slimness of the communication device.
In addition, the conventional sliding module for the sliding-type portable communication device has a long length due to the large-size LCD module, and thus the sliding plate also moves downward together with the sliding of the sliding portion, causing interference between neighboring components, which leads to scratches along the surface, and the LCD module and the sliding portion are highly likely to be damaged in case where the communication device is dropped.
Moreover, since the sliding portion of the conventional sliding module has to include the sliding plate, the number of components increases, increasing the unit cost of a product.
Therefore, there is a long-felt need in the art for a device in which a sliding plate is formed integrally on both sides of a sliding housing to reduce the thickness of a sliding-type portable communication device.